Theraflu vs Nyquil – Uses, Dosage, Side Effects, Differences 


It is a combination of phenylephrine, pheniramine, and acetaminophen, that is used to reduce fever and relieve pain.

Pheniramine is an antihistamine which reduces the natural chemical histamine in the human body. This neurotransmitter can produce symptoms of itching, sneezing, cough, runny nose, and watery eyes. Phenylephrine is in a class of drugs called nasal decongestants that work by reducing swelling of the blood vessels in the nasal passages.

Acetaminophen is a medication used to treat fever and pain. Its therapeutic effects are similar to salicylates, however, it lacks antiplatelet, anti-inflammatory, and gastric ulcerative attributes.


It is typically used to treat flu and cold symptoms, like – sore throat, headaches, cough, body pain and aches, sinus and nasal congestion.


The usual recommended dose is one packet every 4 hours, while symptoms persist, but do not take more than 5 packets in 24 hours.

Side Effects And Precautions

Common side effects may include:

  • blurred vision;
  • dryness of the nose, eyes, and mouth;
  • ringing in the ears;
  • problems with concentration or memory;
  • feeling irritable or restless;
  • drowsiness;
  • constipation;
  • dizziness;
  • stomach pain;
  • mild nausea.

Rare side effects may include:

  • slow, shallow breathing;
  • fast or uneven heart rate;
  • little urinating;
  • rapid pulse;
  • unusual weakness;
  • chest pain;
  • severe dizziness or anxiety;
  • easy bruising or bleeding;
  • tremor;
  • seizure;
  • hallucinations;
  • shortness of breath;
  • confusion;
  • anxiety;
  • severe headaches;
  • yellowing of the skin or eyes;
  • clay-colored stools;
  • dark urine;
  • loss of appetite;
  • pain in the upper stomach.

Ask your healthcare professional if it is safe for you to take this drug if you:

  • use methotrexate (a chemotherapy agent and immune system suppressant);
  • drink more than 3 alcoholic beverages a day;
  • are on hormone replacement therapy or birth control pills;
  • have a liver disease;
  • use HIV or AIDS drugs;
  • have a blockage in your digestive tract;
  • use drugs to treat mental illness;
  • take tuberculosis medicine;
  • take heart or blood pressure medication;
  • use antifungal drugs;
  • take arthritis or gout medications (including gold injections);
  • use antibiotics;
  • use drugs for Parkinson’s disease (part of a group of conditions called motor system disorders);
  • take bladder medicine, like – fesoterodine, darifenacin, tolterodine (an antimuscarinic medicine which is used for symptomatic treatment of urinary incontinence), oxybutynin, or solifenacin;
  • take steroids, like – prednisone;
  • take bronchodilators, like – tiotropium or ipratropium;
  • take seizure medication;
  • use a nonsteroidal anti-inflammatory drug, like – naproxen (Aleve), ibuprofen (Motrin, Advil), diclofenac, celecoxib (Celebrex), meloxicam, and indomethacin;
  • have an overactive thyroid;
  • take potassium supplements;
  • have an adrenal gland tumor (pheochromocytoma);
  • take medications to treat stomach ulcer, excess stomach acid, irritable bowel syndrome, or motion sickness;
  • have chronic bronchitis;
  • have emphysema (a long-term, progressive disease of the lungs which mainly causes shortness of breath);
  • have a cough caused by smoking;
  • have a cough with mucus;
  • suffer from chronic obstructive pulmonary disease;
  • have asthma;
  • have coronary artery disease;
  • have heart disease;
  • have high blood pressure;
  • use cholesterol-lowering drugs, like – Lipitor, Crestor, Simcor, Atorvastatin, Simvastatin,
    Pravachol, Zocor, Zetia, Vytorin.
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It is not recommended to drink alcohol while taking this medication.


It is a combination of doxylamine, dextromethorphan, and acetaminophen, that are used to treat fever, headaches, sneezing, sore throat, cough, and runny nose in adults and children 12 years and older.

Doxylamine is an antihistamine medication which reduces the effects of the natural chemical histamine in the human body. This neurotransmitter can produce symptoms of sneezing, watery eyes, itching, and runny nose. Dextromethorphan is a cough suppressant that affects the cough reflex in the brain which triggers coughing. Acetaminophen is a fever reducer and pain reliever.


It is typically used to treat headaches, body aches, fever, cough, runny nose, itching, sneezing, and watery eyes caused by the common cold, allergies, or the flu.


The usual recommended dose is 30 mL every six hours.

Side Effects And Precautions

Common side effects may include:

  • dry mouth or nose;
  • sleep problems (insomnia);
  • blurred vision;
  • headaches;
  • dry eyes;
  • constipation;
  • feeling excited or restless (particularly in children);
  • upset stomach;
  • mild skin rash;
  • trouble concentrating;
  • drowsiness;
  • mild dizziness.

Rare side effects may include:

  • little or no urinating;
  • seizure (convulsions);
  • uneven heartbeats;
  • severe headaches;
  • pounding heartbeat;
  • restless muscle movements;
  • slow or shallow breathing;
  • tremor;
  • unusual bleeding;
  • severe drowsiness;
  • easy bruising;
  • feeling light-headed;
  • hallucinations;
  • confusion;
  • yellowing of the skin or eyes;
  • pale skin;
  • clay-colored stools;
  • dark urine;
  • loss of appetite;
  • pain in the upper stomach.

Ask your healthcare provider if it’s safe for you to take this drug if you have other medical conditions, particularly:

  • glaucoma;
  • a history of alcoholism;
  • overactive thyroid;
  • liver disease;
  • if you take potassium supplements;
  • monoamine oxidase inhibitors, because they can cause serious or life-threatening complications;
  • pheochromocytoma (tumor of the adrenal gland);
  • bladder obstruction;
  • blockage in your digestive tract;
  • coronary artery disease;
  • heart disease.
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Pregnancy & Breastfeeding

There are no human studies regarding the safe use of these medicines by pregnant or breastfeeding women.

Theraflu vs Nyquil – Differences

Theraflu (active ingredients – pheniramine, acetaminophen, and phenylephrine) is a combination medicine that is used to relieve symptoms due to a cold, including body aches, fever, nasal and sinus congestion, and sore throat.

Nyquil (active ingredients – doxylamine, dextromethorphan, and acetaminophen) is a combination medicine that is used to treat fever, headache, cough, body aches, sneezing, runny nose, and sore throat caused by the common cold, allergies, or the flu. According to the data, this medication is easier on your stomach and has fewer side effects than other similar medications.

6 Natural Remedies For Colds & Flu

#1 Sleep

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Sleep promotes the influence of cytokines stimulating the interaction between T-helper cells and antigen-presenting cells required for the body to fight virus infections.

Also, a lack of restful sleep has been strongly associated with numerous medical disorders from dementia to a negative impact on your immune system.

#2 Turmeric

It is high in antioxidants (like curcumin) that help the body to fight inflammation.

#3 EchinaceaEchinacea

This medicinal herb is one of the best known herbal cold treatments. To use it, it is recommended to mix 20 drops of an echinacea tincture with warm water a few times per day.

#4 Garlic

It is an amazing and potent natural antiviral that can help with flu, colds, and stomach flu.

#5 Physical Exercise

Moderate exercise, like walking, can help alleviate some of the cold symptoms, however, don’t overdo it.

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#6 Vitamin C-Rich Foodsd

Vitamin C has long been known to support the immune system. Foods high in vitamin C include – kiwis, bananas, oranges, mangoes, bell peppers, blueberries, strawberries, guavas, blackberries, papaya, kale, spinach, broccoli, tomatoes, cabbage, and Brussels sprouts.


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